Discovery of Three Apparent Novae in M81

ATel #4844; K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic), O. Vaduvescu (ING, La Palma, Spain), P. van Oers (ING, La Palma, Spain & University of Southampton, UK & University of Amsterdam, Netherlands)
on 27 Feb 2013; 13:51 UT
Credential Certification: Jose L. Prieto (jose@obs.carnegiescience.edu)

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We report the discovery of three apparent novae in the M81 galaxy on a co-added 3200-s narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma in ~1.4" seeing on Feb. 25.132 UT. The new objects are visible on individual 400-s frames and well visible on the co-added image (see the finding chart linked below), but are not present on numerous narrow-band H-alpha archival images from the INT down to limiting magnitude as faint as H-alpha = 22.5.

We also obtained Sloan r' (on Feb. 25.146) and Sloan i'-band (on Feb. 25.144) images that helped us to classify the objects. Strong H-alpha emission together with relative faintness in the Sloan r' and i' bands is consistent with evolved nova phenomenon and supports the classification of the objects as novae.

Designations, positions, and offsets of the new objects from the center of M81 are summarized in the following table:

 
  TOCP designation    CBAT designation  R.A. (J2000)  Dec. (J2000)  Offset R.A.  Offset Dec. 
 
PNV J09552647+6903073  M81N 2013-02b?   09 55 26.47   +69 03 07.3     35.9" W      47.8" S 
PNV J09553974+6905219  M81N 2013-02c?   09 55 39.74   +69 05 21.9     35.2" E      86.8" N 
PNV J09560368+6859586  M81N 2013-02d?   09 56 03.68   +68 59 58.6    163.7" E     236.5" S 
 

The photometry of the new objects as well as of PNV J09555177+6902549 (ATel #4630) and PNV J09555123+6901482 (ATel #4794 and #4813) obtained with the INT + WFC is summarized here:

 
 
  TOCP designation        H-alpha mag       Sloan r' mag      Sloan i' mag 
 
PNV J09552647+6903073    18.55 +/- 0.05    20.68 +/- 0.08     20.7 +/- 0.1 
PNV J09553974+6905219    19.57 +/- 0.09    21.4  +/- 0.1      21.8 +/- 0.3 
PNV J09560368+6859586    20.4  +/- 0.15        > 22.1            > 22.1 
PNV J09555177+6902549    21.9  +/- 0.3         > 22.2            > 21.9 
PNV J09555123+6901482    20.5  +/- 0.15    21.9  +/- 0.2         > 22.0 
 

Two of the three new objects are visible also on a co-added prediscovery 1170-s R-band CCD image taken by K. Hornoch and J. Vrastil on Feb. 7.002 with the 0.65-m telescope at Ondrejov, namely PNV J09552647+6903073 and PNV J09560368+6859586 at R = 20.3 +/- 0.2 mag and R = 20.8 +/- 0.25 mag, respectively. The PNV J09553974+6905219 is not visible on the image down to R = 21.7 mag.

This work is based on observations made with the Isaac Newton Telescope (INT) operated on the island of La Palma by the Isaac Newton Group (ING) in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias (IAC).

Finding chart